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New Member

ospf virtual links and backbone area 0

I created a simple packet tracer topology and connected three ospf areas in the next manner: area0 - area1 - area2 . I verified that area 2 couldn't ping the rest of the network thus I configured a virtual link through area 1. Now area 2 is connected to area 0. My question is why area 1 sees area 2 in its routing table but area 2 cannot see area 1?

Some ip route results:

R0#show ip rout

--- omitted output ---

     192.168.0.0/30 is subnetted, 4 subnets

C       192.168.0.0 is directly connected, FastEthernet0/0

O       192.168.0.4 [110/2] via 192.168.0.2, 02:19:32, FastEthernet0/0

                    [110/2] via 192.168.0.9, 02:19:32, FastEthernet0/1

C       192.168.0.8 is directly connected, FastEthernet0/1

O       192.168.0.12 [110/2] via 192.168.0.9, 01:19:14, FastEthernet0/1

     192.168.1.0/30 is subnetted, 4 subnets

O IA    192.168.1.0 [110/3] via 192.168.0.2, 01:11:32, FastEthernet0/0

O IA    192.168.1.4 [110/4] via 192.168.0.2, 01:11:32, FastEthernet0/0

O IA    192.168.1.8 [110/3] via 192.168.0.2, 01:11:32, FastEthernet0/0

O IA    192.168.1.12 [110/2] via 192.168.0.2, 01:11:32, FastEthernet0/0

     192.168.2.0/30 is subnetted, 3 subnets

O IA    192.168.2.0 [110/3] via 192.168.0.9, 00:43:58, FastEthernet0/1

O IA    192.168.2.4 [110/4] via 192.168.0.9, 00:43:58, FastEthernet0/1

O IA    192.168.2.8 [110/3] via 192.168.0.9, 00:43:58, FastEthernet0/1

R7#show ip route

--- omitted output ---

     192.168.1.0/30 is subnetted, 4 subnets

O IA    192.168.1.0 [110/5] via 192.168.2.1, 00:45:03, FastEthernet0/1

O IA    192.168.1.4 [110/6] via 192.168.2.1, 00:45:03, FastEthernet0/1

O IA    192.168.1.8 [110/5] via 192.168.2.1, 00:45:03, FastEthernet0/1

O IA    192.168.1.12 [110/4] via 192.168.2.1, 00:45:03, FastEthernet0/1

     192.168.2.0/30 is subnetted, 3 subnets

C       192.168.2.0 is directly connected, FastEthernet0/1

C       192.168.2.4 is directly connected, FastEthernet0/0

O       192.168.2.8 [110/2] via 192.168.2.1, 02:20:51, FastEthernet0/1

                    [110/2] via 192.168.2.6, 02:20:51, FastEthernet0/0

Attached there's a print screen of the topology.

Everyone's tags (1)
6 REPLIES
Silver

ospf virtual links and backbone area 0

Hi Daniela,

please, can you upload the .pkt file so we can look at it? Maybe it is some bug, fault of packet tracer.

Best regards,

Jan

New Member

Re:ospf virtual links and backbone area 0

Areas doesn't have routing table, statement is misleading.
Please tell, are checking on internal routers or ABR ?

Sent from Cisco Technical Support Android App

New Member

Re: ospf virtual links and backbone area 0

Ashok, I meant the routing tables of the routers within each ospf area. And as you can see in the image I attached R0 and R7 are internal routers, only R1 and R6 are ABR

Jan, there's the .pkt file. I use version 5.3.3 in ubuntu 11.10... I hope that doesn't pose any compatibility issue :s

New Member

Re: ospf virtual links and backbone area 0

Daniela, internal router just can't have the "O IA" routes i.e. inter-area routes in ospf, you'll see them in ABR/ASBR

either you misconfigured the hostname, i mean,  not as per the exact topology; or it just bug with simulator.

also, i couldn't open your .pkt file, coz i'm using in Win7 & you in linux, ubuntu

I suggest you to do this in GNS3, that'll give almost live device experience, CPT is just a simulator, not a cisco IOS.

But, GNS3 emulates original cisco IOS.

reply me with your findings..

Silver

Re: ospf virtual links and backbone area 0

Hi Daniela,

Thank you for the file, don't worry as I am Ubuntu (12.04) user myself . There should be no issues.

I will take a look on it and let you know as soon as I will finish my other duties.

Bes regards,

Jan

New Member

Re: ospf virtual links and backbone area 0

I repeated the topology and configuration in GNS3. Now I can see in all routers, regardless the area they belong to, routes to every network in the same area and the other two (those routes that come from different area marked as O IA as expected). So I suppose packet tracer has a bug

Ashok, I didn't misconfigure the hostnames and in the attachments you can see that internal routers do show O IA routes.

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